Popping beans, or ñuñas as they are called in Peru, belong to an indeterminately growing varietal group of common beans, whose seeds expand upon toasting. They are a popular snack in parts of Peru and Ecuador, but little known outside their very limited “insular” distribution. While the plant is virtually indistinguishable from regular beans, the seeds of ñuñas tend to be round and opaque. Traditionally, ñuñas have been grown in association with maize, but high-yielding maize is susceptible to logging under the weight of the bean vines. A breeding programme at INIA, Peru, is selecting superior material from farmer selections showing early maturity and determinate growth, in the hope that such selections would succeed in market-oriented cropping systems.